This invention relates to a type of valve known as a xe2x80x9ccheck-valve.xe2x80x9d Check valves are well known and are widely used to control backflow of fluids carrying undesirable contaminants into a fluid supply. These valves have evolved to become highly specialized in their function and operation, and are similar in that they all contain spring-loaded members that are biased toward the valve-closed position until fluid pressure acting on the checking members forces the valves open. Typically, a backflow preventer utilizes two check valves in a conventional serial combination for preventing the backflow of a fluid.
The pressure required to open a check valve is established by governmental regulation and provides a minimum degree of protection against reverse flow. Furthermore, regulations governing backflow preventers require that a check valve and associated parts must be removable for inspection and field service repair without having to remove the valve housing from the fluid conduit system to which it is attached.
In a conventional check valve design, the checking member is a poppet-type check in which the movement of the checking member is linear and remains in the fluid path. The energy required to open these check valves is provided by the fluid and is created at the source by, for example, a pump. The total energy of the fluid in motion is reduced by friction within the pipes and other obstacles in the fluid conduit system. Such obstacles include the checking members, which remain disposed directly in the fluid path once the check valves are open. This energy loss, also known as xe2x80x9cheadloss,xe2x80x9d should be as low as practicable in order to preserve fluid pressure.
Many designs have been proposed to reduce the headloss created by poppet check valves. One design uses a xe2x80x9cswing checkxe2x80x9d type design in which the checking member, also called a clapper, rotates about a fixed hinge pin. The swing check valve is advantageous because it allows the checking member to move out of the path of fluid flow, thereby reducing the headloss associated with conventional poppet-check valves. Clapper and spring assemblies in these conventional swing check designs can be oriented so that as the clapper moves away from the valve-closed position, the torque produced by the spring force about the pivot axis of the clapper through the hinge pin is reduced, thereby further minimizing headloss.
Conventional swing check valves used in backflow preventers generally incorporate the same components. Typically, the clapper in such valves creates a fluid seal across a valve seat. The valve seat surrounds an opening through which fluid would otherwise flow. The valve seat is also usually positioned adjacent to a fluid inlet port in a valve housing of the fluid conduit system and is typically mounted by bolts to the valve housing. As the fluid flows through the port in the downstream direction, the clapper opens by rotating about a hinge pin that is positioned adjacent and parallel to the valve seat face. A helical compression spring is typically used to exert force onto the backside of the clapper. The quantity of water allowed to flow through the swing check valve directly depends on the opening angle of the clapper and the force of the compression spring on the clapper, which in turn acts to oppose the opening of the clapper. The force of the spring on the clapper is a function of the degree of compression between the clapper and some other rigid structure such as the valve housingxe2x80x94fluid pressure must exceed a predetermined magnitude to overcome the spring force on the clapper in order to open the valve.
A toggle-linkage swing check valve is disclosed in Ackroyd, U.S. Pat. No. 5,236,009 (xe2x80x9cthe ""009 patentxe2x80x9d). The swing check valve of the ""009 patent includes a valve assembly having a clapper, spring, and valve seat connected together as a unit. The valve is pivotally mounted at opposite ends to the valve seat and clapper for reorientation of the spring force during movement of the clapper so that the resultant torque applied to the clapper decreases as the clapper moves away from the valve-closed position. A disadvantage to the swing check backflow preventer of the ""009 patent is that when the valve requires maintenance, a cover of the valve housing must be removed and then retaining wires must be removed so that the valve assembly can be manually disengaged from the inlet and then withdrawn from the valve housing. Installation of the valve includes the reverse steps.
Another toggle-linkage swing check valve is disclosed in Dunmire, U.S. Pat. No. 4,989,635 (xe2x80x9cthe ""635 patentxe2x80x9d). The check valve of the ""635 patent includes a valve assembly having a spring, clapper, and valve seat connected together as a unit. The spring is positioned between the clapper and a wall of the valve housing. The wall is preferably a recess defined in the cover of the valve housing. Moreover, the spring is positioned within the recess and pivotally mounted to the clapper for urging the clapper into the valve-closed position so that the torque produced by the spring on the clapper decreases as the clapper pivots away from the valve-closed position. The clapper is attached to the valve seat, which is in turn mounted by bolts to the valve housing. A disadvantage to the swing check valve of the ""635 patent is that replacing the valve assembly requires that the housing cover first be removed. The bolts that attach the valve assembly to the valve housing must then be removed. Only then may the valve assembly be withdrawn from the valve housing, provided that careful control of the spring is maintained. Without such control, the spring becomes free to pivot about its attachment to the clapper once the cover is removed. The valve assembly of the ""635 patent thus presents an awkward handling situation whenever the valve assembly requires assembly, replacement, or maintenance.
Yet another design for swing check valves is the xe2x80x9cRegevxe2x80x9d valve manufactured by A. R. I. Kfar Charuv of Ramot Hagolan, Israel. The valve includes a valve housing having a spring and a clapper that are positioned adjacent an inlet port of a valve housing. The spring includes a spring base, and the clapper has a cam member that remains in continuous engagement with the spring base. The clapper is mounted to the valve housing by a hinge pin. The spring is positioned in a valve housing recess above the clapper and is axially compressible in a direction perpendicular to fluid flow through the valve housing. This forces engagement of the spring base with the cam member to force the clapper toward the valve-closed position. The spring does not vary in its orientation during movement of the clapper as in the toggle-linkage designs discussed above, i.e., the spring is not pivotally mounted at its ends. The torque produced by the spring force on the clapper about the hinge pin is reduced as the clapper moves away from the valve-closed position, thereby minimizing headloss. A disadvantage to the Regev valve is that, in order to replace any component of the valve assembly or replace the entire valve assembly itself, the entire valve housing must be removed from the fluid conduit system and replaced. Furthermore, unlike the valves of the ""009 and ""635 patents, there is no valve assembly disposable within a valve housing in the Regev valve which can be removed from a fluid conduit system without removing the valve housing as required by backflow preventer regulation.
More recent designs for swing-type backflow preventer valves are disclosed in applicant""s U.S. Pat. Nos. 5,711,341 and 5,794,655. Both of these patents disclose a valve housing having a spring and a clapper that are positioned adjacent an inlet port. The spring includes a base, with the rocker arm of the clapper having a roller which remains in continuous engagement with the spring base. The top end of the spring is attached to the interior surface of a hydraulic tap threaded into the valve housing. The clapper is mounted to the valve housing by a hinge pin. The spring is positioned in a valve housing recess above the clapper, and is axially compressible in a direction perpendicular to fluid flow through the valve housing. This forces engagement of the spring base with the cam member to force the clapper toward the valve-closed position. The spring remains in a position perpendicular to the direction of fluid flow at all times.
Therefore, it is an object of the invention to provide a swing check valve which can be easily and readily removed from and inserted into a valve housing of a fluid conduit system by simply removing and installing, respectively, a cover of the valve housing.
It is another object of the invention to provide a swing check valve which has a simple, low maintenance, low friction clapper mechanism that creates low headloss.
It is another object of the invention to provide a swing check valve that has a lever arm attached to the clapper mechanism for generating increased leverage against the clapper mechanism to ease installation of the check valve within the interior of the valve housing.
It is another object of the invention to provide a swing check valve which has a narrow profile, thereby reducing valve height.
It is another object of the invention to provide a swing check valve which has a compression spring which is self-contained and requires no interior attachment.
It is another object of the invention to provide a swing check valve which is energized during final assembly.
It is another object of the present invention to provide a swing check valve which includes a spring that is removably positioned against the valve housing cover and that is oriented for axial compression and expansion of the spring at varying angles within a range of angles, all of which are oblique to the direction of fluid flow through the valve housing.
It is another objective of the present invention to provide a swing check backflow preventer which utilizes two swing-check valves of the present invention in serial combination with one another.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a swing check valve for controlling fluid flow and including a valve housing having a port for fluid flow therethrough. The valve housing includes a removable cover for accessing an interior of the valve housing. A valve assembly is disposed within the interior of the valve housing for controlling the fluid flow through the valve housing. The valve assembly includes a valve seat in fluid communication with the port. A clapper is mounted in the valve housing on a pivotally-mounted rocker arm and is moveable between an open position responsive to fluid flow in a flow direction and a sealed position against the valve seat responsive to fluid flow in an opposite, backflow direction. A spring is captured in the valve housing by the removable cover without attachment to either the cover or valve housing, and normally urges the clapper into the sealed position against the valve seat. A lever arm is pivotally mounted on the rocker arm. The lever arm is moveable between an extended position for providing enhanced leverage against the rocker arm for positioning the clapper and rocker arm within the valve housing, and a closed position for cooperating with the spring for urging the clapper into the sealed position. A first pivot is carried by the spring and cooperates with a mating interior surface of the cover for permitting unattached pivotal movement of the spring relative to the cover. A second pivot is carried by the spring and cooperates with a first mating pivot surface carried on the lever arm for permitting unattached pivotal movement of the spring relative to the lever arm whereby the spring is allowed to pivot within the valve housing responsive to movement of the clapper.
According to one preferred embodiment of the invention, the lever arm is a pair of spaced-apart, opposing planar members defining a void therebetween for receiving the spring.
According to another embodiment of the invention, a spacer interconnects the planar members for maintaining the void therebetween.
According to yet another embodiment of the invention, a third pivot is carried by the rocker arm and cooperates with a second mating pivot surface carried on the lever arm for pivotally mounting the lever arm on the rocker arm.
According to yet another embodiment of the invention, a fourth pivot is carried by the lever arm and cooperates with a third mating pivot surface carried on the rocker arm for permitting pivotal movement of the lever arm relative to the spring and the rocker arm.
According to yet another embodiment of the invention, the first pivot carried by the spring is a ball and the mating interior surface of the cover is a concave surface against which the ball pivots.
According to yet another embodiment of the invention, the second pivot is a convex bearing surface carried by the spring and the first mating pivot surface carried on the lever arm includes at least one roller.
According to yet another embodiment of the invention, the at least one roller moves in an arc along the convex bearing surface as the clapper pivots.
According to yet another embodiment of the invention, the at least one roller is mounted and extends between the opposing planar members.
According to yet another embodiment of the invention, the third pivot is a hinge pin and the second mating pivot surface carried on the lever arm is a complementary opening defined by the lever arm and adapted for receiving the hinge pin therethrough.
According to yet another embodiment of the invention, the third mating pivot surface carried on the rocker arm is a hinge pin and the fourth pivot carried by the lever arm is a pair of concave surfaces against which the hinge pin pivots.
According to yet another embodiment of the invention, each of the concave surfaces is a notch defined by a side edge of a respective one of the planar members.
According to yet another embodiment of the invention, the spring is removably positioned within the valve housing for being axially compressed and expanded between two angles responsive to movement of the clapper, both of which angles are oblique to the direction of flow of fluid through the valve housing.
According to yet another embodiment of the invention, the force of said spring acting on the clapper when the clapper is in the closed position produces a torque that is greater than the torque produced by the spring acting on the clapper when the clapper is in the open position.
According to yet another embodiment of the invention, an alignment compensator is included for preventing out-of-alignment movement of the clapper relative to the valve seat. The alignment compensator includes an alignment spring mounted on the rocker arm and engaging the clapper at a point wherein the point of attachment of the rocker arm to the clapper is between the alignment spring and the pivot point of the rocker arm.
According to yet another embodiment of the invention, the alignment spring is a coil spring.
According to yet another embodiment of the invention, alignment spring is a flat spring.
According to yet another embodiment of the invention, a swing check backflow preventer valve is provided which includes a valve housing having a port for fluid flow therethrough. The valve housing has a pair of spaced-apart removable covers for accessing an interior of the valve housing. A pair of valve assemblies are disposed within the interior of the valve housing for controlling the fluid flow through the valve housing. One of the valve assemblies includes a valve seat in fluid communication with the port. A clapper is pivotally mounted in the valve housing on a rocker arm and is moveable between an open position responsive to fluid flow in a downstream direction and a closed position sealed against the valve seat responsive to fluid flow in an opposite, backflow direction. A spring is captured in the valve housing by one of the removable covers without attachment to either the cover or valve housing. The spring normally urges the clapper into the sealed position against the valve seat. A lever arm is pivotally mounted on the rocker arm and is moveable between an extended position for providing enhanced leverage against the rocker arm for positioning the clapper and rocker arm within the valve housing and a closed position for cooperating with the spring for urging the clapper into the sealed position. A first pivot is carried by the spring and cooperates with a mating interior surface of the cover for permitting pivotal movement of the spring relative to the cover. A second pivot is carried by the spring and cooperates with a mating pivot surface carried on the lever arm for permitting pivotal movement of the spring relative to the lever arm whereby the spring is allowed to pivot within the valve housing responsive to movement of the clapper.
According to yet another embodiment of the invention, the lever arm included in the swing check backflow preventer valve includes a pair of spaced-apart, opposing planar members defining a void therebetween for receiving the spring.
According to yet another embodiment of the invention, the swing check backflow preventer valve includes a spacer interconnecting the planar members for maintaining the void therebetween.
According to yet another embodiment of the invention, the swing check backflow preventer valve includes a third pivot carried by the rocker arm and cooperating with a second mating pivot surface carried on the lever arm for pivotally mounting the lever arm on the rocker arm.
According to yet another embodiment of the invention, the swing check backflow preventer valve includes a fourth pivot carried by the lever arm and cooperating with a third mating pivot surface carried on the rocker arm for permitting pivotal movement of the lever arm relative to the spring and the rocker arm.
According to yet another embodiment of the invention, the second pivot included in the swing check backflow preventer is a convex bearing surface carried by the spring, and the first mating pivot surface carried on the lever arm is at least one roller.
According to yet another embodiment of the invention, the at least one roller included in the swing check backflow preventer valve is mounted and extends between the opposing planar members.
According to yet another embodiment of the invention, the third mating pivot surface carried on the rocker arm and included in the swing check backflow preventer valve is a hinge pin, and the fourth pivot carried by the lever arm is a pair of concave surfaces against which the hinge pin pivots.
According to yet another embodiment of the invention, each of the concave surfaces included in the swing check backflow preventer valve is a notch defined by a side edge of a respective one of the planar members.
According to yet another embodiment of the invention, a swing check valve for controlling fluid flow is provided that includes a valve housing having a port for fluid flow therethrough. The valve housing includes a removable cover for accessing an interior of the valve housing. A valve assembly is disposed within the interior of the valve housing for controlling the fluid flow through the valve housing. The valve assembly includes a valve seat in fluid communication with the port, and a rocker arm having proximal and distal ends. The proximal end is pivotally mounted to the valve seat for being positioned adjacent the port. A clapper is mounted on the distal end of the rocker arm and cooperates with the rocker arm for movement between an open position responsive to fluid flow in a flow direction and a sealed position against the valve seat responsive to fluid flow in an opposite, backflow direction. A spring is captured in the valve housing by the removable cover without attachment to either the cover or valve housing, and normally urges the clapper into the sealed position against the valve seat. A pair of spaced-apart, opposing planar members having a void defined therebetween are mounted on the rocker arm by a hinge pin received within a complementary bore defined by the rocker arm. This permits coupled movement of the planar members between an extended position for providing enhanced leverage against the rocker arm for positioning the clapper and rocker arm within the valve housing and a closed position for cooperating with the spring for urging the clapper into the sealed position. A first pivot is carried by the spring and cooperates with a mating interior surface of the cover for permitting unattached pivotal movement of the spring relative to the cover. A second pivot is also carried by the spring and cooperates with a first mating pivot surface carried on the lever arm for permitting unattached pivotal movement of the spring relative to the lever arm, whereby the spring is allowed to pivot within the valve housing responsive to movement of the clapper.
According to yet another preferred embodiment of the invention, another swing check valve is provided for controlling fluid flow. The swing check valve includes a valve housing having a port for fluid flow therethrough, and a removable cover for accessing an interior of the valve housing. A valve assembly is disposed within the interior of the valve housing for controlling the fluid flow through the valve housing. The valve assembly includes a valve seat in fluid communication with the port, and a rocker arm having proximal and distal ends. The proximal end is pivotally mounted to the valve seat for being positioned adjacent the port. A clapper is mounted on the distal end of the rocker arm and cooperates with the rocker arm for movement between an open position responsive to fluid flow in a flow direction and a sealed position against the valve seat responsive to fluid flow in an opposite, backflow direction. A spring is captured in the valve housing by the removable cover without attachment to either the cover or valve housing and normally urgings the clapper into the sealed position against the valve seat. A void is defined between a pair of spaced-apart, opposing planar members. The planar members are mounted on the rocker arm by a hinge pin received within a complementary bore defined by the rocker arm, for permitting coupled movement of the planar members between an extended position for providing enhanced leverage against the rocker arm for positioning the clapper and rocker arm within the valve housing, and a closed position for cooperating with said spring for urging the clapper into the sealed position. A convex pivot surface is carried by the spring and cooperates with a mating concave interior surface defined by the cover for permitting pivotal movement of the spring relative to the cover. A convex bearing surface is also carried by the spring and cooperates with at least one roller interconnecting the planar members for permitting unattached pivotal movement of the spring relative to the lever arm whereby the spring is allowed to pivot within the valve housing responsive to movement of the clapper.
An embodiment of a method according to the present invention is provided for installing a valve assembly in a valve housing. The method includes the step of providing a valve housing having a port for fluid flow therethrough. The valve housing includes a removable cover for accessing an interior of the valve housing. The method also includes the step of providing a valve assembly adapted for disposal within the interior of the valve housing for controlling the fluid flow through the valve housing. The valve assembly includes a valve seat in fluid communication with the port, and a clapper adapted for being mounted in the valve housing. The clapper is pivotally mounted on a rocker arm and is moveable between an open position responsive to fluid flow in a flow direction and a sealed position against the valve seat responsive to fluid flow in an opposite, backflow direction. The valve assembly also includes a spring adapted for being captured in the valve housing by the removable cover without attachment to either the cover or valve housing for normally urging the clapper into the sealed position against the valve seat, and a lever arm pivotally mounted on the rocker arm. The lever arm is moveable between an extended position for providing enhanced leverage against the rocker arm for positioning the clapper and rocker arm within the valve housing, and a closed position for cooperating with the spring for urging the clapper into the sealed position. The valve assembly also includes a first pivot carried by the spring and adapted for cooperating with a mating interior surface of the cover for permitting unattached pivotal movement of the spring relative to the cover, and a second pivot carried by the spring for cooperating with a first mating pivot surface carried on the lever arm. Mounting the second pivot in this manner permits unattached pivotal movement of the spring relative to the lever arm whereby the spring is allowed to pivot within the valve housing responsive to movement of the clapper. The method further includes the steps of removing the cover from the valve housing, thereby permitting access to the interior of the valve housing, and disposing the valve assembly in the valve housing. The valve assembly is disposed in the valve housing by moving the lever arm to the extended position, positioning the clapper and rocker arm within the valve housing by using the extended lever arm to provide enhanced leverage against the rocker arm, moving the lever arm to said closed position, positioning the spring within the valve housing, and replacing the cover on the valve housing. This captures the spring in the valve housing and permits the spring to cooperate with the closed lever arm for urging the clapper into the sealed position.